Communication devices that perform wireless communication conforming to the IEEE 802.11 series are being widely used. Communication devices conforming to the IEEE 802.11 series adopt an access scheme called CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance). CSMA/CA specifies that before transmission of signals, carrier sensing be performed for measuring a radio field intensity for a frequency channel on which the signals will be transmitted. In carrier sensing, the radio field intensity for a width of 20 MHz, which is one frequency channel specified in IEEE 802.11, is measured.
As a result of carrier sensing, if the measured radio field intensity does not exceed a predetermined threshold, signals are transmitted; if the measured radio field intensity is greater than or equal to the predetermined threshold, signals are not transmitted.
In IEEE, IEEE 802.11ax is under examination as a successor to IEEE 802.11ac (PTL 1). In IEEE 802.11ax, it is being examined that one frequency channel is further divided into a plurality of frequency bands and the plurality of frequency bands are utilized by different devices to perform communication simultaneously.